// Copyright (C) 1999-2001 by Jason Hunter <jhunter_AT_acm_DOT_org>.
// All rights reserved.  Use of this class is limited.
// Please see the LICENSE for more information.

package com.baomidou.framework.upload.multipart;

import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;

/**
 * A <code>MacBinaryDecoderOutput</code> filters MacBinary files to normal files
 * on the fly; optimized for speed more than readability.
 * 
 * @author Jason Hunter
 */
public class MacBinaryDecoderOutputStream extends FilterOutputStream {
	private int bytesFiltered = 0;
	private int dataForkLength = 0;

	public MacBinaryDecoderOutputStream(OutputStream out) {
		super(out);
	}

	public void write(int b) throws IOException {
		// Bytes 83 through 86 are a long representing the data fork length
		// Check <= 86 first to short circuit early in the common case
		if (bytesFiltered <= 86 && bytesFiltered >= 83) {
			int leftShift = (86 - bytesFiltered) * 8;
			dataForkLength = dataForkLength | (b & 0xff) << leftShift;
		}

		// Bytes 128 up to (128 + dataForkLength - 1) are the data fork
		else if (bytesFiltered < (128 + dataForkLength) && bytesFiltered >= 128) {
			out.write(b);
		}

		bytesFiltered++;
	}

	public void write(byte b[]) throws IOException {
		write(b, 0, b.length);
	}

	public void write(byte b[], int off, int len) throws IOException {
		// If the write is for content past the end of the data fork, ignore
		if (bytesFiltered >= (128 + dataForkLength)) {
			bytesFiltered += len;
		}
		// If the write is entirely within the data fork, write it directly
		else if (bytesFiltered >= 128 && (bytesFiltered + len) <= (128 + dataForkLength)) {
			out.write(b, off, len);
			bytesFiltered += len;
		}
		// Otherwise, do the write a byte at a time to get the logic above
		else {
			for (int i = 0; i < len; i++) {
				write(b[off + i]);
			}
		}
	}
}
